The 27-year-old has been used sparingly by Pep Guardiola since making the switch to the Premier League champions from Bournemouth in 2020, featuring in just 24 league appearances during his two-year stay so far.
The likes of John Stones, Aymeric Laporte and Ruben Dias have all been ahead of Ake in the pecking order at the Etihad Stadium, and as a result, City are reportedly willing to allow the Dutchman to move on during the summer transfer window.
Thomas Tuchel's Chelsea have emerged as the frontrunners to secure Ake's signature, and transfer expert Romano has reported that the Blues have agreed terms with the defender ahead of sealing a move.
Tweeting from his official Twitter account on Friday, Romano said: "Chelsea have full agreement with Nathan Aké on personal terms. Man City are aware of the situation on the player side, but still waiting to receive the official bid.
"City want around £40/45m for Aké and plan is to replace him with a new centre back in case he leaves."
Chelsea are on the lookout for several defensive reinforcements ahead of the 2022-23 campaign following the departures of Antonio Rudiger and Andreas Christensen on free transfers, as well as the impending exits of both Cesar Azpilicueta and Marcos Alonso to Barcelona.
Juventus' Matthijs de Ligt is one of several targets along with Ake, but with the Dutchman's reported desire to join Bayern Munich, Chelsea are said to be pursuing a move for Napoli's Kalidou Koulibaly instead.
Should Ake make the move to Stamford Bridge, he would be returning to the club in which he came through the ranks as a youngster, before being sold to Bournemouth for £20m in 2017 following two loan spells with the Cherries.